Supply Self Adjustment for Systems and Methods Having a Current Interface

ABSTRACT

A sensor system having a current interface includes a supply and current interface, an electronic control unit and an enhanced initialization sensor. The supply and current interface is configured to receive a supply voltage. The electronic control unit is coupled to the supply and current interface. The enhanced initialization sensor is coupled to the supply and current interface. The enhanced initialization sensor is configured to initialize the supply and current interface at a suitable current level to mitigate erroneous information. measurement system

BACKGROUND

Automotive systems are complex systems that include computers andcomponents to operate and monitor operation of automotive vehicles. Thesystems typically include a processor that controls and monitors engineoperation and the like. The system generally operates various controlsystems that perform automotive functions. By monitoring, minor problemscan be identified and corrected before becoming major problems.

Sensors are used in automotive systems to monitor characteristics orproperties relevant to operation. The sensors then convey theinformation to an electronic control unit, which performs actions inresponse. The sensors monitor information such as speed, temperature,and pressure.

In interface systems using current, the sensor uses the same wires usedto convey the information that are used to receive supply power. Onecommon technique to convey the information to the ECU is to use firstand second current levels to transfer the information digital. However,problems can occur if the supply power is insufficient.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a sensor system using a currentinterface.

FIG. 2 is a graph depicting examples of voltage and current levels foran enhanced initialization sensor.

FIG. 3 is a block diagram illustrating an electronic control unit.

FIG. 4 is a block diagram illustrating an enhanced sensor that can beutilized with the system.

FIG. 5 is a flow diagram illustrating a method of operating a currentinterface.

DETAILED DESCRIPTION

The present invention will now be described with reference to theattached drawing figures, wherein like reference numerals are used torefer to like elements throughout, and wherein the illustratedstructures and devices are not necessarily drawn to scale.

Systems and methods are disclosed that interface systems using multiplecurrent levels, such as automotive systems. The systems and methodsmitigate generation and transmission of erroneous information duringinitialization sequences.

Initialization or initialization sequences typically occur in interfacesystems when transitioning from an OFF or low power state to an ONstate. For example, an automotive interface system may initialize uponstarting a car.

FIG. 1 is a diagram illustrating a sensor system 100 having a currentinterface. The interface uses multiple current levels to transferinformation. The system 100 initializes a standard current for theinterface to a suitable level that compensates for hysteresis andmitigates the transfer of inaccurate or erroneous information.

The system 100 includes a voltage supply 102, an enhanced initializationsensor 104, an electronic control unit 106 and a supply and currentinterface 108. The voltage supply 102 provides a DC power source atvoltage. Generally, for automotive applications the voltage is about 11to 12 Volts DC. The voltage supply 102 can be provided by a suitablepower source, such as an automotive battery, lead acid battery,alternator, and the like.

The supply and current interface 108 is a multipurpose set of wires orlines that provide both power and data transfer by current levels. Theinterface 108 is coupled to the voltage supply 102, which provides theDC power to other components coupled to the interface 108.

The electronic control unit (ECU) 106 operates as a controller for thesystem 100. The unit 106 transfers data, including control information,with other components in the system. The ECU 106 is configured to storeinformation, analyze information, determine responses, control sensorsand components, and the like. For example, the ECU 106 can be configuredto adjust a throttle according to received information from sensors onvelocity. As another example, the ECU 106 can be configured to activateair bag deployment in response to information from a pressure sensor.

It is appreciated that if information received by the ECU 106 isinaccurate, problems can occur. For example, if rotations per minute(RPM) are incorrect, an improper speed is determined. If a fuel sensordoesn't initialize properly, the amount of remaining fuel may bedetermined improperly.

The enhanced initialization sensor 104 is configured to measure one ormore characteristics or properties and provide the measured informationto the ECU 106 by the supply and current interface 108. The measuredcharacteristics or properties can include, for example, pressure,temperature, motion, magnetic fields, and the like. Further, the sensor104 can be a pressure sensor, antilock brake sensor (ABS), and the like.The sensor 104 receives power from the voltage supply 102, also by wayof the supply and current interface 108.

In one example, the measured information is based on a signal derivedfrom changes in a magnetic field. For example, a pole wheel or the likemay be used to generate magnetic fields that vary according to arotational speed of an automotive wheel.

It is appreciated that the voltage supply 102 includes intermittentsupply. For example, a car battery and/or alternator may fail at leasttemporarily causing the voltage supply 102 to fall below a levelrequired for proper operation of the sensor 104. This level is alsoreferred to as a reset level and provides a threshold where the sensor104 is more likely to provide incorrect measured information. If thelevel is below the reset level, the sensor 104 doesn't have enoughvoltage or power to perform properly. The measured information may omitinformation or provide incorrect information.

The enhanced initialization sensor 104 includes enhanced initializationfunctionality. Thus, when the voltage supply 102 is restarted orreactivated, the sensor 104 initializes to a standard/default current ata suitable current level. This occurs when the voltage supply 102 hasrisen to or above a release threshold. The suitable level is selected soas to be high enough to mitigate erroneous transmissions and/orerroneous data. The release threshold is typically slightly above thereset threshold. In one example, the suitable current level is set to ahighest current level for an interface protocol. The protocol has aplurality of current levels. Additionally, the sensor 104 initializes toa suitable voltage value associated with the suitable current. Thesuitable voltage is high enough to also mitigate the voltage supply 102falling to the reset level.

In another example, an interface protocol uses a current level of 7 mAand a current level of 14 mA for transferring data. In this example,once the voltage supply 102 rises to at least the release threshold, thecurrent level is set to the suitable level of 14 mA instead of 7 mA. Asa result, any change in current across the interface 108 is to use alower current. The lower current necessarily leads to an increase in thevoltage level of the voltage supply 102. Otherwise, for example, anincrease in the interface current leads to a decrease in the voltagelevel, which can lead to insufficient operating voltage for the sensor104 and/or resetting the sensor 104. Thus, the initialization process ofsetting the current to a suitable level avoids or mitigatesunnecessarily resetting the sensor 104 and providing incorrect data.

Resetting the sensor 104, particularly during or right afterinitialization, can lead to current variation waveforms that look likemeasured data or other information, but in actuality are not. Thiserroneous information can even be misinterpreted by the ECU 106 andcause improper actions to be taken or required actions not to beperformed.

FIG. 2 is a graph 200 depicting examples of voltage and current levelsfor an enhanced initialization sensor. The examples are described withreference to the sensor 104 and system 100 of FIG. 1, described above.However, it is appreciated that variations of the system 100 arecontemplated. Further, it is appreciated that the values shown in thegraph are provided for illustrative purposes and that other suitablevalues may be used with the system 100 and variations thereof.

The graph 200 is described in terms of current IDD and voltage VDD of asupply and current interface, such as the interface 108, coupled to anenhanced sensor, such as the enhanced sensor 104. The current IDD isprovided in mA and the voltage VDD is provided in volts.

An upper portion of the graph 200 depicts IDD along a Y-axis and timealong an X-axis. A lower portion depicts VDD along a Y-axis and timealong an X-axis. The upper and lower portions show the IDD and VDD ofthe interface at points in time along the Y-axis.

Initially, on the left, the VDD and IDD start at or near zero. Thiscould be for a battery or other power source slowly turning on itssupply of power to a voltage supply coupled to the interface. As thevoltage increases, the enhanced initialization sensor 104 startsincreasing the current IDD. The IDD continues to increase as the VDDincreases until the IDD reaches the suitable/default level of 212, whichin this example is 14 mA. The level 212 is also a highest current levelof an interface protocol. The VDD continues to increase until the VDDreaches the release threshold 206. Until the VDD reaches the releasethreshold 206, the sensor 104 is inactive in that it does not providemeasured information and/or transmit data.

Upon reaching the release threshold 206, the sensor 104 can startproviding information. In this example, the sensor 104 beginstransmitting measured data by adjusting current levels of the IDD. Thesensor 104 uses the upper level 212 and a lower level 210 in thisexample. Upon reaching the release threshold, the sensor 104 has driventhe IDD to the upper level 212, thus the only possible change in the IDDis to a lower current, which results in an increase in VDD. As a result,undesirably lowering the VDD to the reset level 204 is mitigated.

An increase in IDD causes a decrease in VDD and a decrease in IDD causesan increase in VDD. This change is due to the change in current levelmultiplied by a demodulation resistor used in the electronic controlunit. In this example, there is an increase in the VDD. In this example,at time 214, the change is a decrease in IDD, which leads to an increasein VDD. Additionally, the voltage at 214 is also referred to as asuitable or safe voltage in that a later increase in current, such as at216, is generally not likely to or does not fall to the reset threshold204.

At a second time 216, there is an increase in IDD, which leads to adecrease in VDD. However, by this time 216, the voltage supply 102 hassufficiently initialized that the VDD does not fall to the resetthreshold 204.

The depicted example does eventually show a decrease in VDD where VDDfalls to the reset threshold. At this point, the sensor 104 isdeactivated and providing of the measured data is halted.

FIG. 3 is a block diagram illustrating an electronic control unit 106.The electronic control unit (ECU) 106 can be utilized with thesystem100, described above. The unit 106 is described here withadditional details for illustrative purposes. However, it is appreciatedthat variations of the electronic control unit 106 are contemplated.

The ECU 106 includes a demodulation resistor 312 and a controller 310.Other components, such as a memory, interface, and the like may also bepresent. The ECU 106 is coupled to a supply and current interface 108and to ground 314. By using the interface, the ECU 106 is configured totransfer data, including control information, measured information, andthe like, with other components of the system.

The controller 310 includes a processor or other circuitry configured toreceive information and control other components and is connected to theinterface 108 and ground 314. The ground 314 is considered to be part ofthe interface 108. The controller 310 is configured, in one example, tostore information, analyze information, determine responses, controlsensors, and the like. The controller obtains measured information bycurrent levels of the supply and current interface 108.

The demodulation resistor 312 is also coupled to the interface 108 andthe ground 314. In order to maintain suitable levels, the demodulationresistor 312 has a selected resistance value. The resistor 312 can beconfigured or sized to mitigate unwanted fluctuations at the interface108. The resistance value is typically within a specified range, but canvary. For example, one manufacturer may use a resistor with a resistanceof 15 ohms while another may use a resistance of 75 ohms. However, othercomponents coupled to the interface 108 generally assume or are designedfor the largest possible resistance. This can lead to wasted powerconsumption, operating voltage, and the like. The system 100 and theenhanced interface 104 are not required to be based on the largestresistance of the protocol as it is more tolerant.

FIG. 4 is a block diagram illustrating an enhanced sensor 104 that canbe utilized with the system 100. The enhanced sensor 104 is configuredto measure one or more characteristics or properties and to provide themeasured information to other components, such as the ECU, by a supplyand current interface.

The enhanced sensor 104 is described with additional details forillustrative purposes. It is appreciated that variations are permitted.

The sensor 104 is coupled to a supply and current interface 108. Theinterface provides power and is also used to transfer data, includingproviding measured information. The sensor 104 includes a voltageregulator 416, a reset generator 418, a signal conditioning component422, an initialization component 440, a sensing element 420, and acontrollable current component 424.

The voltage regulator 416 receives power 436 from the interface 108 andis configured to provide a regulated power 426. In one example, thereceived power is at a voltage level of about 10-13 volts and theregulated power is at about 3-5 volts. The reset generator 418 isconfigured to turn off data transfer if the regulated power 426 isinsufficient and turn ON data transfer if the regulated power 426 issufficient. If the regulated power 426 is insufficient, the othercomponents of the system 400 may operate improperly and supply erroneousdata. Thus, the reset generator 418 mitigates transfer of erroneous databy comparing the regulated power 426 with a reset threshold and arelease threshold. The release threshold is selected so that regulatedpower 426 falling below the threshold could or is likely to lead toerroneous data. Upon the regulated power 426 being insufficient or at orbelow the reset threshold, the reset generator 418 sends a signal 428 tothe signal conditioning component 422 indicating a RESET. Upon theregulated power 426 being sufficient or at or above the releasethreshold, the reset generator 418 sends a signal 428 to the signalconditioning component 422 indicated a RELEASE.

The signal conditioning component 422 is configured to provide acondition signal 430 to the controllable current component 424. Thecondition signal 430 sets the current component 424 to a selectedcurrent level of a plurality of current levels. In one example, theplurality of current levels include 5 mA and 12 mA, 7 mA and 14 mA, andthe like.

The signal conditioning component 422 provides the signal 430 based onone or more inputs, including an initialization signal 442 and a sensingsignal 432. The sensing signal 432 indicates the selected level based ona sensed property. The initialization signal 442 supersedes the sensingsignal and sets the selected level to be at a suitable current level ofthe plurality of current levels. In one example, the initializationsignal 442 is set to a highest current level of the plurality of currentlevels.

As stated above, the sensing element 420 generates the sensing signal432 based on a sensed property and/or characteristic 434, such as amagnetic signal. The sensing signal 432 modulates or varies the selectedlevel to convey measured information. The sensing element 432 can be apressure sensor, magnetic/speed sensor, temperature sensor, and thelike. The sensing element 420 is powered by the regulated power 426.

The initialization component 440 is configured to generate theinitialization signal 442 to set the selected level to the suitablelevel at the time of initialization. During initialization, the signalconditioning component 422 receives the regulated power 426, however thepower 426 is typically not high enough. This information is provided bythe reset signal 428. Once the reset signal is OFF, the initializationcomponent 440 sets the initialization signal 442 to select the suitablelevel for a period of time, such as a clock cycle or a portion of aclock cycle. After the period of time, the initialization signal 442does not set the selected current level and normal operation is assumed.

The initialization component 440 sets the suitable level to a value thatmitigates a subsequent reset due to a voltage drop over the next cycleor two. The suitable level is set to avoid an increase or substantialincrease in current consumed at the interface 108 over the next cycle ortwo. The component 440 is shown as a separate component in FIG. 4,however it is appreciated that its functionality can be integrated intoother components, such as the signal conditioning component 422.

The controllable current component 424 sinks current 438 at a pluralityof levels according to the signal 430. The current 438 is varied toconvey information across the interface 108. In one example, theinterface 108 uses a first level at 7 mA and a second level at 14 mA.The voltage regulator 416 consumes about 2 mA of current 436. Thus, thecurrent 438 is varied from 5 mA to 12 mA to yield the first and secondlevels.

The enhanced sensor 104 mitigates transferring erroneous data by settingits current to a suitable current level. This mitigates improper orundesired resets due to increases of current that lead to decreases insupply voltage of the interface 108. Additionally, this is accomplishedwithout a need to monitor the voltage of the interface 108.

FIG. 5 is a flow diagram illustrating a method 500 of operating acurrent interface. The method 500 initializes a current level or outputof an enhanced sensor in order to mitigate providing erroneous data.

The method begins at block 502, wherein a suitable current level for anenhanced sensor is selected. The suitable current level is selected tomitigate a voltage drop at an interface and to maintain the voltage atthe interface at a level above a reset threshold. In one example, thesuitable current level is selected to be a highest level of a pluralityof current levels used for the interface.

A voltage regulator provides a regulated power at block 504. Theregulated power typically starts at a lower voltage and graduallyincreases toward a final voltage. The regulated power is at a lowervoltage than a supply voltages and is used by one or more componentswithin the enhanced sensor.

A release signal is generated by a signal conditioning component uponthe regulated power increasing to or beyond a release threshold at block506. This threshold is a voltage at which components of the enhancedsensor typically operate. The release threshold is above the resetthreshold, but may be below the final voltage.

The sensor output is initialized to the suitable level at block 508. Thesensor output is initialized to the suitable level prior to theoccurrence of conveying measured information. In one example, the sensoroutput is initialed prior to the release signal. An initializationcomponent configures the signal condition component to set the sensoroutput to the interface at the suitable level for a period of time. Theperiod of time is also selected to mitigate a voltage drop at theinterface below the reset threshold.

A sensor obtained measured information and the signal conditioningcomponent varies the current level of the sensor output to provide themeasured information at block 510. The measured information is conveyedvia the interface, such as the interface 108 described above, to othercomponents, such as an electronic control unit.

While method is illustrated and described below as a series of acts orevents, it will be appreciated that the illustrated ordering of suchacts or events are not to be interpreted in a limiting sense. Forexample, some acts may occur in different orders and/or concurrentlywith other acts or events apart from those illustrated and/or describedherein. In addition, not all illustrated acts may be required toimplement one or more aspects or embodiments of the disclosure herein.Also, one or more of the acts depicted herein may be carried out in oneor more separate acts and/or phases.

It is appreciated that the claimed subject matter may be implemented asa method, apparatus, or article of manufacture using standardprogramming and/or engineering techniques to produce software, firmware,hardware, or any combination thereof to control a computer to implementthe disclosed subject matter (e.g., the systems shown in FIGS. 1, 2,etc., are non-limiting examples of system that may be used to implementmethod(s)). The term “article of manufacture” as used herein is intendedto encompass a computer program accessible from any computer-readabledevice, carrier, or media. Of course, those skilled in the art willrecognize many modifications may be made to this configuration withoutdeparting from the scope or spirit of the claimed subject matter.

A sensor system having a current interface includes a supply and currentinterface, an electronic control unit and an enhanced initializationsensor. The supply and current interface is configured to receive asupply voltage. The electronic control unit is coupled to the supply andcurrent interface. The enhanced initialization sensor is coupled to thesupply and current interface. The enhanced initialization sensor isconfigured to initialize the supply and current interface at a suitablecurrent level to mitigate erroneous information.

An enhanced initialization sensor system is disclosed. The systemincludes a voltage regulator, a signal conditioning component and aninitialization component. The voltage regulator is configured to receivea supply voltage from an interface and to provide a regulated power. Thesignal conditioning component is configured to receive the regulatedpower and to control a current level based on one or more inputs. Theinitialization component is configured to receive the regulated powerand to initialize the signal conditioning component to a suitablecurrent level.

A method of operating a current interface is disclosed. A regulatedpower is provided. A release signal is generated upon the regulatedpower reaching a release threshold. A sensor output is initialized to asuitable current level by a signal conditioning component. Additionally,an interface coupled to the sensor output is set to the suitable currentlevel.

In particular regard to the various functions performed by the abovedescribed components or structures (assemblies, devices, circuits,systems, etc.), the terms (including a reference to a “means”) used todescribe such components are intended to correspond, unless otherwiseindicated, to any component or structure which performs the specifiedfunction of the described component (e.g., that is functionallyequivalent), even though not structurally equivalent to the disclosedstructure which performs the function in the herein illustratedexemplary implementations of the invention. In addition, while aparticular feature of the invention may have been disclosed with respectto only one of several implementations, such feature may be combinedwith one or more other features of the other implementations as may bedesired and advantageous for any given or particular application.Furthermore, to the extent that the terms “including”, “includes”,“having”, “has”, “with”, or variants thereof are used in either thedetailed description and the claims, such terms are intended to beinclusive in a manner similar to the term “comprising”.

1. A sensor system having a current interface, the system comprising: asupply and current interface; an electronic control unit coupled to thesupply and current interface; and an enhanced initialization sensorcoupled to the supply and current interface and configured to providemeasured information to the electronic control unit via the supply andcurrent interface and configured to initialize the supply and currentinterface at a suitable current level to mitigate erroneous information.2. The system of claim 1, wherein the supply and current interfacereceives a supply voltage and supplies the supply voltage to theelectronic control unit and the enhanced initialization sensor.
 3. Thesystem of claim 2, wherein the supply voltage is at a voltage of about10 to 20 Volts.
 4. The system of claim 1, wherein the supply and currentinterface has a plurality of current levels for communication.
 5. Thesystem of claim 4, wherein the plurality of current levels include 7 mAand 14 mA.
 6. The system of claim 1, wherein the electronic control unitincludes a demodulation resistor coupled to the supply and currentinterface.
 7. The system of claim 6, wherein the suitable current levelis independent of the demodulation resistor.
 8. The system of claim 1,wherein the enhanced initialization sensor is configured to initializethe supply and current interface to a suitable starting voltage.
 9. Thesystem of claim 1, wherein the initialization component sets thesuitable current level to a highest current of a plurality of currentlevels used by the supply and current interface.
 10. The system of claim1, wherein the initialization component maintains the suitable currentlevel for a period of time to mitigate a voltage drop at the supply andcurrent interface.
 11. The system of claim 1, wherein the enhancedinitialization sensor includes a sensing element configured to obtainthe measured information.
 12. The system of claim 11, wherein theenhanced initialization sensor includes a voltage regulator configuredto supply a regulated power to the sensing element.
 13. An enhancedinitialization sensor system comprising: a voltage regulator configuredto receive a supply voltage from an interface and to provide a regulatedpower; a signal conditioning component configured to receive theregulated power and to control a current level based on one or moreinputs; and an initialization component configured to receive theregulated power and to initialize the signal conditioning component to asuitable current level.
 14. The system of claim 13, wherein theregulated power is at a lower voltage than the supply voltage.
 15. Thesystem of claim 13, further comprising a reset generator configured toreset and release the signal conditioning component according to theregulated power.
 16. The system of claim 13, further comprising asensing element configured to receive the regulated power and to providea sensing signal to the signal conditioning component as an input of theone or more inputs.
 17. The system of claim 13, further comprising acontrollable current component configured to controllably sink currentfrom the interface according to the signal conditioning component.
 18. Amethod of operating a current interface, the method comprising:providing a regulated power; upon the regulated power reaching a releasethreshold, generating a release signal; and initializing a sensor outputto a suitable current level by a signal conditioning component prior tothe release signal being generated.
 19. The method of claim 18, furthercomprising setting an interface to the suitable current level.
 20. Themethod of claim 19, further comprising selecting the suitable currentlevel to mitigate the regulated power falling below a reset threshold.